1. Field of the Disclosure
The disclosure generally relates to a method for manufacturing a semiconductor device. More specifically, the disclosure relates to a method for pattern formation which can overcome the resolution limit of a lithography process in fabricating a semiconductor device.
2. Brief Description of Related Technology
Recently, a double exposure process has been performed to form a fine pattern of semiconductor devices to overcome the resolution limit of exposer equipment. The conventional process is as follows.
Referring to FIGS. 1a and 1b, an underlying layer 12, a first hard mask layer 13, a first anti-reflection film 14 and a first photoresist film 15 are sequentially formed over a semiconductor substrate 11. A first region among the entire surface is exposed using a first exposure mask 16, and the exposed photoresist film 15 is developed to form a first photoresist pattern 15′. The hard mask layer 13 generally is a bi-layer of amorphous carbon layer and inorganic hard mask layer.
Referring to FIGS. 1c and 1d, the first anti-reflection film 14 is etched with the first photoresist pattern 15′ as a mask, thereby forming a first anti-reflection pattern 14′. After etching the first hard mask layer 13 with the first anti-reflection pattern 14′ as a mask, a first hard mask pattern 13′ is formed.
Referring to FIGS. 1e and 1f, a second hard mask layer 17, a second anti-reflection film 18 and a second photoresist film 19 are sequentially formed over the first hard mask pattern 13′. A second region among the entire surface is exposed alternately with the first region using a second exposure mask 20, and the exposed photoresist film 19 is developed to form a second photoresist pattern 19′. The second hard mask layer 17 preferably has different etching selectivity with the first hard mask layer 13.
Referring to FIGS. 1g and 1h, the second anti-reflection film 18 is etched with the second photoresist pattern 19′ as a mask, thereby forming a second anti-reflection pattern 18′. After etching the second hard mask layer 17 with the second anti-reflection pattern 18′ as a mask, a second hard mask pattern 17′ is formed.
Referring to FIG. 1i, an underlying layer 12 is etched with the first and second hard mask patterns 13′, 17′ as a mask, thereby obtaining a fine pattern 12′.
In the above-described conventional method, however, a photoresist film, an anti-reflection film and a hard mask layer must be coated and etched twice respectively, in order to form a fine pattern. Therefore, the overall process becomes complicated, resulting in the reduction of the total yield.